a. Field of the Invention
This invention relates to the polyurethane polymer art, and more particularly to curable polyurethane polymers in which a proportion of the NCO terminations have been reacted with certain silicon-containing materials.
The invention further relates to sealant compositions containing novel silicon modified polyurethane polymers, which sealants are package stable, moisture curable, and adhere well to a variety of substrates without the use of a primer.
B. Description of the Prior Art
Polyurethane polymers containing trialkoxysilane terminations, and sealants comprising such polymers are known in the art.
In U.S. Pat. No. 3,627,722 the preferred reactant with from 5 - 50% of the NCO groups on a polyurethane prepolymer is a monofunctional methyl-aminopropyltrimethoxy silane. Substitution of a difunctional amino silane, viz., gamma-aminopropyltriethoxysilane, produced unsatisfactory results.
U.S. Pat. No. 3,632,557 discloses producing a useful reaction product of a polyurethane prepolymer with a difunctional aminosilane, viz., gamma-aminopropyltrimethoxysilane, but here the patentees employ a stoichiometric excess of aminosilane. Thus, the product contains no NCO terminations, only silicon-containing terminations.
U.S. Pat. No. 3,309,261 discloses an adhesive composition comprising a mixture of a polyurethane resin and an aminosilane.
U.S. Pat. No. 3,372,083 discloses use of the reaction product of toluene diisocyanate and gamma-aminopropyltriethoxysilane in a polyurethane sealant composition.
Other reference of general interest in showing the state of the art are U.S. Pats. Nos. 3,387,016; 2,296,471; 2,956,044; 3,088,847; 3,471,541; 3,477,901; 3,829,529; 3,900,679; 3,246,048; 3,450,791; 3,575,910, 3,627,836; 3,644,566; 3,650,812; 3,794,694; 3,808,287; 3,829,527; and 3,893,496.